The suspension was imposed at Don Muang airport, used mainly for domestic flights. The facility is located in northern Bangkok, the area of the capital most severely affected by the worst flooding that Thailand has seen in decades.
The BBC reported that the landing strip was expected to remain closed for a week.
The Suvarnabhumi Airport in eastern Bangkok, which handles most international traffic, was reported to be still operating.
Thailand has been inundated by three months of monsoon downpours that have left more than 360 people dead. Thai officials have warned that the deluge could last several more weeks.
Water from drenched central areas of the country was now running south to the sea and officials were trying to drain it to the east and west, but the immense volume of water had forced them to open sluice gates into the city. Seven districts of the capital were now reported to be at risk of flooding.
The domestic airport was also being used as an evacuation center and as headquarters for the government's flood relief operations, the BBC reported.
In an effort to help people cope with the flooding, Thai authorities have declared a five-day holiday in several provinces, including Bangkok, to run from Thursday through Monday, the news agency said.
-- Ann M. Simmons in Los Angeles
Photo: Flood victims watch television at the Don Muang airport, which has become an evacuation center. Flooding has closed the airport's runway. Credit: Paula Bronstein / Getty Images